Method for making methine dyestuffs



Patented Oct. 30, 1951 UNITED. STATES PATENT OF METHOD FOR MAKING METHINE DYESTUFFS Harry Derek Edwards, Ilford, England, assiglioi to Ilford Limited, Ilford, England, a British company No Drawing. Application September 22, 1949, Se-

rial No. 117,266. In Great Britain October 2,

7 Claims.

This invention relates to methine dyestuffs and particularly to dyestuffs having a substituted methine chain.

In my co-pending application Serial No. 117,265, filed September 22, 1949, now Patent No. 2,534,112, there is described the production of intermediates of the general formula:

CN R:

OOR1

CN /CHa 5:0

OOCHa As explained in the said application, the compounds of the said formula may exist in the alternative stereoisomeric form represented by the formula:

Accordingly the formula LOOK].

used herein and in the following claims is to be understood to include the stereoisomeric form represented by the said alternative formula,

Where in suchintermediates the-group-Rz is an alkyl or aralkyl group the formula may be rewritten:

OOR

where R; is a hydrogen atom or an alkyl group. The CH2 groupin such compounds has been found to be reactive and according to the present invention dyestuifs are obtained by reacting a compound of the general formula:

CN CHaRA OQRi where R1, R3 and R4 have the meanings assigned to them above, with an alkyl or aralkyl quaternary salt of a five-membered or six-membered heterocyclic nitrogen compound having a'thioether-group in a or 7 position to the quaternary nitrogen atom.

The course of the reaction is believed to be as follows:

In the foregoing formulae R5 represents an alkyl or aralkyl group and R6 represents an alkyl group, e. g. any of those mentioned above, X represents an acid radicle, e. g. chloride, bromide, iodide, sulphate or p-toluene sulphonate, n is nought or one, and D is the residue of a fivemembered or six-membered heterocyclic nitrogen nucleus. The residue D may be, for example, the residue of any of the types of heterocyclic nuclei commonly employed in photographic sensitising dyes, e. g. thiazoles, oxazoles, selenazoles and their polycyclic homologues, such as those of the benzene, naphthalene, acenaphthene and anthracene series, pyridine and its polycyclic homologues such as quinoline and a and B naphthoquinolines, lepidines, lindolenines, diazines such as pyrimidines and quinazolines, diazoles such as thio-p,p-diazole, oxazolines, thiazolines,

and selenazolines. The polycyclic compounds of these series may be substituted in the carbocyclic rings by one or more groups such as alkyl, aryl, amino, hydroxy, alkoxy and methylene-dioxy groups or by halogenatoms.

The reaction is preferably effected, in the presence of abasic condensing agent, e. g. a basic organic agent such as pyridine or triethylamine.

In one form of the invention the heterocyclic nitrogen compound is converted to an alkyl' orr,

aralkyl quaternary salt and this simultaneously reacted with the thioether compound by fusing together the heterocyclic nitrogen compound, an-

alkyl or aralkyl salt and the thioether compound;

The dyes produced conform to formula above and it will be noted that where :Rris a hydrogen atom these have the samestrueture-as; or a stereoisomeric structure with, the dyes produced according to the process of British-Patent;

No. 610,569. As stated therein, such dyes are valuable sensitizers for ph oto graphic emulsions.

' The following examples will serve to illustrate the invention, but are not to be regarded as limiting the invention in anyway:

Ethyl 4- (3-methyl-2 3 -dihydrobenzthiazolylidene-2-) 3-ethylthio-2 cyano-Z butenoate ys a srmaptllfii-C; hes ys allisae.

tion, from ethyl alcohol, gave yellow/red needlea:

t- 1 r nd .furtherre rystallisati n;from.-

ethyl, alcohol raised the m pt. to 128;

yestulf. in orporated in a gelatinosilyer; iodobromide emulsion, imparts a bandsofjensig; t v x extendin .21 0, about; 550 .;rnh..with;a;stron peak maximum at 530 m .1

Ethyl 4 (3 methyl-2:3-dihydrobenathiaaolylidem-2 )-3 methylthio-Z-cyano-2-butenoate Ethyl 2-cyano-,3-methylthio:2floutenoate (.925 gm.; 7.005 mol.) was fusediwith methyl para toluene sulphonate, (.93 gm.; .005'mol.) and 2- methylthio-benzthiazole (.905 gm.; .005 mol.) for 16 hours at 100 C.

Ethyl alcohol cc.) and triethylamine (7 5,. cc. .005 mol.) were thenaddedandthe; whole" boiled gently under reflux for; 10' minutes. 0001- ing and dilution gave orange crystals. 'M'.pt;-157- C.*Crystal1isation from methyl; alcohol-gave m. pt. 164"C.j-' Recrystallisation from methyl alcohol gave m. pt. 166C: 1

' This dyestuif, incorporated in a gelatino-silveriodobromideemulsion, imparts a band of sensitivity'" extending to 540- m with a peakmaxi mum at 525 m V Ethyl4- [3--et;hyl-2 :3-dihydro-benzthiazolylidene- 2-l 3-methylthz'o-2-cyano-2butenoateL I Ethyl 2-cyanoe3-methylthioe2-butenoate (.925;

gm.; .005 mol.) was fused withmethylmercapto: benzthiazole .905 gm.-; .005 mol.). ,and. ethyl para."

gm.; 0.002 .mol.) @was, fused with methyl; p-toluene sulphonate (0.398 gm. .0025 mol.) and 2-,me1thylthio ben'zthiazole (0.362 g 5.002. mol.) 51 .24

4 toluene sulphonate (.995 gm.; .005 mol.) for 6 hours at 140 C.

The mixture was dissolved in ethyl alcohol (15 cc.) and boiled gently under reflux with triethylamine (.75 00.; .005 mol.) for 10 minutes. On cooling and dilution; orange/red crystals separated. M. 'pt. 145 C. crystallisation from methyl alcohol gave m. pt. 146 C. Reorystallisation from methyl alcohol gave no increase in meltingqpointi EXAMPLE 4 Ethyl 4- (3-methyl-2 :3-dihydro-4:5-benz-benz- 1 thiazolylidene 2 )-3-methylthio-2-cyano-2- butenoate '2--methyl.mercapto 49 naphthathiazole (1.165 gms.; .O05 mol.) was fused with methyl para toluene sulphonate (.93 gm.; .005 mol.) for 8 hours; at. C. Ethyl-2-cyano-3-methylthio- Z-butenoate (.925 gm. .005 mol.) was added and the mixture-boiled gently; under reflux for 10 minutes-in ethyl alcohol (20 cc.) with triethyl amine (.75 cc.; .005 mol.). On coolinganddilu-Q tion oran e/red crystals separated. M. pt. 207 C. Crystallisation-from methyl f alcohol gave m.;.pt.. 212?. C... Rrecrystallisationfrom methyl.- alcohol gave msp't. 213% EXAMPLE" 5 Ethyl 4- 3 -methyl-2 :3-dihydr'o-5 :6 -di0a:ymethylene benzthiazolylidene 2 3-ethylthio-2- cyano-Z-butenoate 2 methyl mercapto dioxymethylene..benzthia=.. zole (.223 gm.; .001 mol.) was fusedwith. methylv para toluene sulphonate.-( .186 .gm..; .001- 11101;) .for. 8 -hours at C. Ethyl-.2-cyano-3-ethylthio- Z-butenoate (.2 gm.; .001 mol.) .was added and, the mixture boiled gently .under reflux for. 10. minutes in ethyl alcohol (10 cc.). with triethylr amine (.3 cc.; .001 mol.). On coolingand dilution orange/red crystals separated... M.-pt. 216 C.- (No second crop was obtained on further dilution.) Crystallisation fromizethyl alcohol gave m. pt. 258 C. Recrystallisation from ethyl alcohol gave m. pt. 260 C;'

2 methyl mercaptolfi naphthathiazole (.446 gm; .002 mol.) was fused with methyl para toluene sulphonate (.372 "gm; .002 mol.) for 8 hours at,120.; C., Ethyle2-cyano-3-ethylthioe2- butenoate. .4 gm.; .002 mol.). was added. and the mixture boiled gently under reflux foralo minutes in ethyl alcohol (10 cc.) with triethylamine kii 00.; .002 mol.). On cooling and dilution orange/red crystals separated. M. pt. 221 C. (No second crop was obtained on further dilution.) crystallisationq froml ethyl alcohol gave m. pt. 222 C. Further crystallisation did not raise the melting point.

EXAMP LE. 7 Ethyl 4- (3-methyZ-2 :3-dz'hydro-5 .6-dioxymethylene benzthz'azolylz'dene 2-)-3-methylthio-2- cyano-butenoate thio.-2-'butenoate ;(.0.62;..:gm.;.. .0003. mol.);alwas added and the mixture boiled gently under reflux for 10 minutes in ethyl alcohol to.) with triethylamine (.05 cc.; .0003 mol.). on cooling and dilution orange/red crystals separated. -M. pt. 249 C. (No second crop was obtained on further dilution.) Crystallisation from methyl alcohol gave m. pt. 252 C. Recrystallisation from methyl alcohol gave no. pt. 253 C.

EXAMPLE 8 Ethyl 4 (B-methyl-Z:3-dihyclrobenzthiazolylidene-'2-) -3-isopropylthi0-2-cyano-2-butenoate- EXAMPLE 9 Ethyl-4-[3 methyl 2:3-dihydrobenzthiazolylidene-2-l-3-n butylthio-Z-cyano-2-butenoate Methyl mercapto benzthiazole (.362 gm.; .002 mol.) was fused with methyl para toluene sulphonate (.364 gm.; .002 mol.) and ethyl-2-cyano- 3-n-butylthio-2-butenoate (.454 gm.; .002 mol. at 100 C. for 16 hours. Ethyl alcohol (10 cc.) and triethylamine (.3 00.; .002 mol.) were then added and the mixture boiled gently under reflux for 10 minutes giving a yellow solution. On cooling and dilution orange crystals separated. M. pt. 147 C. Crystallisation from methyl alcohol gave m. pt. 152 C. Recrystallisation from methyl alcohol gave m. pt. 153 C.

EXAMPLE 10 Ethyl 4-[3 methyl 2:3-dihydrobenzthiaeolylidene-Z-l -3-benzylthio -2-cyano-Z-butenoate Methyl mercapto benzthiazole (.362 gm.; .002 mol.) was fused with methyl para toluene sulphonate (.364 gm.; .002 mol.) and ethyl-Z-cyano- 3-benzylthio-2-butenoate (.524 'gm.; .002 mol.) at 100 C. for 16 hours. Ethyl alcohol (10 cc.) and triethylamine (.3 00.; .002 mol.) were added and the mixture boiled gently under reflux for 10 minutes giving an orange/ yellow solution. On

cooling and dilution orange crystals separated.

M. pt. 180 C. crystallisation from methyl alcohol gave m. pt. 154 C. Recrystallisation from methyl alcohol gave m. pt. 155 C.

EXAMPLE 1 1 Methyl 4 (3-methyl-2:3-clihydrobenzthiazolylidene-2-) -3-ethylthio-2-cyano-2-butenoate EXAMPLE 12 Methyl 4 (3-methyZ-2:3-dihyd1'obenzthiaolylidene-2-) -methyZthio-2-cyano-2 b'utenoate 3 Methyl mercapto benzthiazole (.724 gm; .004; mol.); was fused with -methyl para-toluene sulphonate' (.728 gm.;' .004 mol.) at C. fort-l2 hours. Ethylv alcohol (20 cc.) .triethy1amine- (.6

cc.;. .004 mol.) and methyl-2-cyano-3-meth'yl.-"

thio-2-butenoate (.78 gm.; .004 mol.) wereradded and the mixture boiled gently unclerrefiux for 10 minutes givinga yellow solution; .On cooling and dilution .orange/red crystals separated.- M.

pt. 207C. crystallisation from methyl-alcohol. gave no. pt. 212 C. -Recrystallisationfrom.

methyl alcohol gave m. pt. 213 C. r

Corresponding compounds may be prepared by strictly analogous processes" from quaternary salts of 2-ethylthio and Z-methylthio derivatives of quinoline, selenazole, :benzselenazole;;zoxazole,.;

benzoxazole, thiazoline, selenazoline, oxazoline and 33 dimethyl indolenine. The quaternary salts in each case may be methyl, ethyl or higher alkyl or benzyl iodides, bromides, hydrogen sulphates or p-toluene sulphonates.

What I claim is:

1. Process for the production of methine dyestuffs which comprises reacting a compound of the general formula:

L SR3 COR;

where R1 is an alkyl group, R3 is selected from the group consisting of alkyl and aralkyl groups and R4 is selected from the class consisting of the hydrogen atom and alkyl groups, with a compound selected from the class consisting of alkyl and aralkyl quaternary salts of five-membered and six-membered heterocyclic nitrogen compounds of the type used in cyanine dyes, having a thioether group in one of the a and '7 positions to the quaternary nitrogen atom.

2. Process for the production of methine dyestuffs which comprises reacting a compound of the general formula:

l SR3 OORI where R1 is an alkyl group, R3 is selected from the group consisting of alkyl and aralkyl groups and R4 is selected from the class consisting of the hydrogen atom and alkyl groups, with a compound selected from the class consisting of alkyl and aralkyl quaternary salts of five-membered and six-membered heterocyclic nitrogen compounds of the type used in cyanine dyes, having a thioether group in one of the a and '7 positions to the quaternary nitrogen atom, the reaction being effected in the presence of an organic basic condensing agent.

3. A process for the production of the methine dyestuff ethyl 4- (3 -methyl-2 3 -dihydrobenzthiazolylidene-2-) 3-ethylthio-2 cyano-2 butenoate which comprises reacting ethyl 2-cyano-3-ethylthio-2-butenoate, methyl p-toluene sulphonate and 2-methylthio-benzthiazole.

4. A process for the production of the methine dyestuff ethyl 4-(3 methyl 2:3 dihydro 4:5- benz-benzthiazolylidene-2-) 3 methylthio-2- cyano-Z-butenoate which comprises reacting 2- ifiethyi mfcapto: .5 naphthathiazole, methyl para. toluene, su1phonate..and.. 'ethyl-2-cyanoramethylthioi z-butenoate.,

5. A process for the production of the methine dyestuffiz ethyl -:(3-..methy1e21-:3edihydroL-5: 6:-.dioxymethylene t:benzthia,zo1y1idene-.-2;--) 3 -\-'.ethyl'- ti'zioe.2ecyano2-butenoa,t;e *which v comprises; reacting zmethylnmercaptofdioxymethylene benzthriau'zole,- methyl: para; t01uene-sulphonate v and;

ethylefi+cyanor-3-ethylthioz-2-butenoa.te.

6; A, process: for the: production at the methine dyestufl".ethyl".4 -(31-:methy1123:3 dihydroiizfie benz-benzthiazolylidene -.V 25-); -.z3--'.ethy1thio 12.!-

v YeyanoeZ-butenoate-which comprises reacting 2- "m'eth-yl mercapto p knaphthathiazole, methyl para toluene sulphonate and ethy1-'2cya,no.+3:-ethylthio-2butenoate'.

; 'ZiaAhrocessi for. the production of .the: methine HREFERENKES CITED The following-references are 'of record in z the file of this vpatent:

UNITED STATES PATENTS Number Name ,v Date,

2,177,401 wBrooker Oct. 24,1939 2;310;640 'Kendall Feb. 9, 1943 2,319,547 .Kendall May 18., 1943 FOREIGN PATENTS Number Country Date .610,5 69 "Great Britain. l -1948. 

1. PROCESS FOR THE PRODUCTION OF METHINE DYESTUFFS WHICH COMPRISES REACTING A COMPOUND OF THE GENERAL FORMULA: 